Governor for brake air compressor



Sept. 3, 1957 R. w. FISHWOOD ETAL 2,804,878

GOVERNOR FOR BRAKE AIR COMPRESSOR Filed June 29, 1954 INVENTORS AGENT on Nm INN 0N United States Patent O 2,804,878 7 GOVERNOR FOR BRAKE AIR COMPRESSOR Rollin W. Fishwood, Vancouver, Wash., and Walter J. Evans, Portland, reg., assignors to Power Brake Equipment Company, of Oregon Application June 29, 1954, Serial No. 440,232,

3 Claims. 01. 1s7 102 This invention relates generally to air brake equipment adapted for use with automotive transportation equip ment. More particularly this invention provides an improved governor adapted to control the operation of an unloader for an air compressor used to supply activating a1r for such brake equipment.

Air compressors for this use are usually connected to run continuously while the motive power engine of the equipment is running. The air from the compressor discharged to an air accumulator or storage tank the air I pressure within which is normally held within preset limits by the compressor governor and unloader.

A simple means, and one for which the present invention is adapted, to govern the air supplied bya continu-j ously running compressor to a storage tank, is to hold the inlet valve or valves of the compressor open wheni no air is required from the compressor and to allow the valves to operate normally when air is required.

It is therefore a principal object of this invention to provide such a governor with an improved means adapted to be pressure controlled and at and above a higher Portland, 0reg., a corporation ass sts Patented Sept. 3, 1957 Ice Like reference numerals refer to like parts in the two figures of the drawing.

Referring now to the drawing, Fig. 1 is a side elevation and partial sectional view of the governor of this invention schematically arranged for use with an air com-- pressor having an unloader and an air storage tank, while Fig. 2 is a vertical sectional view taken along the line 22 of Fig. 1.

In Fig. 1 is shown schematically and fragmentally an 7 .mosphere through inlet port 16, past inlet valve 17 to the interior of cylinder 11 and forcing the air at high pressure from cylinder 11 out through outlet port 18 past valve 19, through valve chamber 23, cover 20, and tubing 21, to receiver or storage tank 22. Valves 17 and 19 are biased towards their respective seats at ports 16 and 18 by 5 springs 24 and 25.

Mounted on cylinder head 12 and secured thereto by bolts 26 is unloader 27 shown as including a flexible dia-- phragm 28 clamped at its outer edge between upper body.

part 29 and lower body part 30. Rod 31 secured to diaphragm 28 and guided in bearing 32 in body part is.

adapted when the center of diaphragm 28 is depressed to contact disk 33 secured to compressor inlet valve stem 34 and hold inlet valve 17 in open position away from its seat at inlet port 16. Spring 35 biases diaphragm 28 upwards towards a normal position at which rod 31 is preset air pressure at the outlet of an air compressor tooperate the unloader to open and hold open respectively an inlet valve of the compressor and thereafter at a lower preset air pressure at the outlet of the air compressor to operate the unloader to restore the inlet valve to its proper function.

It is a. second object to provide such a governor which is simple in construction, low in first cost, easy to adjust and easy to service,

It is a third object to provide such a governor in which the air pressure responsive means has a normal position of rest from which it is adapted to be moved at a higher preset air pressure to energize the unloader and a limit position of movement adjustable to vary the airpressure difference between the higher preset air pressure and a lower preset air pressure at which .the air responsive means is adapted to de-energise the unloader and to return to its normal position. l

It is a fourth object to provide such a'governor with means adapting the air responsive means to be," biased towards its normal position of rest by a resilient means adjustable to determine the pre-set high air pressure;

It is a fifth object to provide such a governor with means adapting the air responsive means at any pressure of the air at the outlet of the compressor to'be'urged away from its normal position with a smaller force while at its normal position and with a larger force after move ment away from its normal position has started.

It is a sixth object to provide such a governor in which all adjustments of the preset air pressures can be made from outside the body of governor without removing any parts, connections or covers.

How these and other objects are attained is explained in the following description referring to the attached drawing of a preferred form of the governor of this invention.

retracted not to interfere with the normal operation of valve 17.

Tube 36 secured into upper body part 29 by hollow plug 37 connects the hollow interior of body part 29 with outlet port 38 of governor 39 into which it is sealed by hollow plug 40.

Tube 41 sealed into tank 22 is for the purpose of supplying'air under pressure as required to the air brake system of the vehicle on which it is mounted.

Tube 42 sealed at one end into tank 22 and at its other end into governor lower body part 43 by plug 44 con-.

nects the interior of tank 22 with inlet valve port 45 of governor 39 through air entrance channel 46, screen chamber 47 and screen 48 secured int-o screen chamber.

47 by plug cap 49,

Governor 39 is secured by bolts 51 through holes 52 in lower body 43 to bracket 50 conveniently secured on the vehicle chassis.

Flexible diaphragm 53 secured by cap screw 76 between mating surfaces of upper body part 54 and lower body part 43 divides the interior cavity of the governor into a first compartment 55 and a second compartment 56.

. Hollow cylindrical range adjusting screw 57 threadedly engaged in upper body 54 and secured by lock-nut terminates at its lower end in exhaust valve seat 58 surrounding exhaust port 69.

Secured to diaphragm 53 by central rivet 59 is cx 56 with the atmosphere through the interior ofadjusting;

pressed into lower body 43 as shown and sealed into" upper body 54 by O-ring 73.

It should be noted that adjusting spring 62 normally biases diaphragm 53 downward and with valve disk 61 seated on its seat 74 about inlet port 45 the vertical adjustment of screw 65 relative .to seat 74 determines the pressure at which air fromtank 22 can unseat valve 61 from its seat 74.

' Again it should be noted that the threads on thinner and outer surfaces of adjusting screw '57 are. of 'equal pitch and of the same right-hand form so that by'holding screw 65 stationary and turning screw 57 the vertical position of screw 65 will not be changed but the position of exhaust valve seat 58 with respect to screw 65"can be varied to vary the biasing force of spring 62 on diaphragm 53 when exhaust valve 60 is seated on its seat 58.,

The operation of the governor'is as follows. When the compressor is running to build up air pressure inftank 22 the compressor valves are in normal operation, the bias of spring 62 holds inlet valve 61 of governor 39 seated on .inlet valve seat 74, exhaust valve60 is away from itstseat 58, compartment 56 is open .to atmosphere, the interior of upper body part 29 of unloader 27 is at atmospheric pressure and spring 35 biases unloader diaphragm upward with rod 31 out of interference with compressor inlet valve stem 34. i

When the pressure in tank 22 builds up to a value preset by the adjustment of pressure screw 65, the tank pressure acting on the small exposed area of governor inlet valve 61 lifts valve 61 E its seat 74'and the inrush of air under pressure into compartment 55 bounded by' diaphragm 53 quickly overcomes the bias of spring 62 and completes the throw of diaphragm 53 to furtherlift valve 61 from its seat 74 and close exhaust valve 60 onto its seat 58. The restriction of passages 70, 71, and 72 is sufiicient to complete the described valve operation before the air pressure ,in compartment 56 is equalized through passages 70, 71, and 72 with the pressure in compartment 55 after which the full tank pressure is exerted on .the top of unloader diaphragm 28 to push rod 31 downward and hold inlet valve 16 of the compressor open so that compressor outlet valve 19 remains on its seat and the compressor is inoperative although still in motion.

, When this operation of the governor has been completed the pressure'in both compartmentsSS and 56'will be equalized with the tank pressure and the exhaustvalve will be held closed against the bias of spring 62by the tank pressure operating on the diaphragm 53 and exhaust valve 60 over the area of the exhaust port 69 which is greater than the area of the inlet port 45.

-It should particularly be noted that the biasing force exerted by spring 62 towards movement oi exhaust valve 60 away from its seat 58 is adjustable by upward or downward adjustment of range adjusting screw 57 while the position of pressure adjusting screw 65 is unchanged for it is seen that the compression of spring 62 when valve 6 0 is seated onseat 58 of port 69 will be decreased as the vertical distance between abutment 64 of pressure screw.

65 and'seatSS is increased. As the pressure of spring 62 on the diaphragm rivet 59 is decreased the lower the tank through tube 41 and the pressure in tank 22 has'lowered to the value pres-set by theposition of range adjusting screw 57, spring 62 quickly will-move diaphragm 53 to move exhaust valve'60 from its seat 58 and move'inlet;

valve 61 onto its seat 74. With this diaphragm action the cycle of governor operation is completed. Compressed air from tank 22 is blocked at the governor inlet port 45, the interior of the governor has been opened to atmosphere, the unloader is de-activated and the compressor is restored to its useful operation of supplying air under pressure to tank 22.

It is a particular feature of this invention that the sudden or snap action of diaphragm 53 in either of its direction of operation to open one valve and close the other is made possible by the method shown of taking advantage of the relative port and diaphragm areas disclosed and taking advantage of the instantaneous air pressure drops through lines and restricted passages as indicated.

Having thus recited some of the objects of our invention, illustrated and defined a preferred form in which the invention may 'be practiced and described the'operation thereof, we claim: a

1. An pressure controller adapted to activate at a pre-set lower pressure an air pressure increasing means and at a pre-set higher pressure to de-activate said air pressure increasing means, said controller comprising means forming a first compartment having an inlet-port communicatingwith the air whose pressure is to be controlled, means forming a second compartment having an exhaust duct, movable wall means separating said first and second compartments, restricted flow air conduit means connecting said first and second compartments, said -wall including means adapted at a first position to close said inlet port, a hollow range adjusting screw axially adjustablypositioned in said exhaust duct, one end of said range adjusting screw being adapted to form an exhaust port, a hollow pressure adjusting screw axially adjustably positioned in said hollow range adjusting screw, said second compartment being adapted to communicate with the atmosphere through said exhaust port and said adjusting screws, said pressure screw having an abutment formed therein, a pressure spring within said pressure screw axially thereof and strained between said abutment and said Wall to bias said wall towards said first position, said wall including means adapted at a second position to close said exhaust port, all of said means adapting said wall at an inlet air pressure determined by the position of said pressure adjusting screw tomove with a snap action from said'first position to said second position and at a reduced inlet air pressure determined by .the position of said range adjusting screw to move with a snap action from said second position to said first position.

,"2. A pneumatically controlled and operated governor valve for an air compressor adapted to supply air to a storage tank and equipped with pneumatically operated unloading meanstforholding open an inlet valve of said air compressor, said governor valve comprising a hollow body divided interiorly into an inlet chamber and an outlet chamber by a flexible diaphragm carrying an inlet valve axially aligned thereon in said inlet chamber and an exhaust valve axially aligned thereon in said outlet chamber, orifice means adapting said inlet chamber to be connected to said storage tank, means adapting said outlet chamber -to be connected to said unloading means, said hollow body being formedwith ahollow cylindrical open ended extension of said outlet chamber formed axially of said diaphragm, a hollow cylindrical axially positionable sleeve movablysealed in said extension, the inner end of said sleeve forming an exhaust valve seat for said exhaust valve, arestrictedopening connecting the interior of said'sleeve with the atmosphere, an adjustment plug axially --positionable in said sleeve, cooperating means formed on said extension said sleeve and said plug .for

relatively axially positioningsaid extension said sleeve and said. plugas jdesired from outside said body, a partition formed in said inlet chamber between said diaphragm andisaid orificean inlet valve seat formed on sa d part1- tion axially of said inlet valve, an inlet port formed through said partition within said inlet valve seat, a restricted flow conduit connecting said inlet chamber and said outlet chamber and coil spring means within said sleeve-between said plug and said exhaust valve adapted to bias said exhaust valve towards its open position and said inlet valve towards its closed position.

3. The valve of claim 2 in which the eflfective diameter of said inlet valve seat is less than the effective diameter of said exhaust valve seat and the effective diameter of said exhaust valve seat is less than the effective diameter of said diaphragm whereby when said inlet valve is closed on its seat and the pressure in said inlet chamber from said tank is great enough to overcome the bias of said spring on said diaphragm said inlet valve will beg-in to rise from its seat and air pressure through said inlet valve will be applied over the effective diameter of said diaphragm to snap said inlet valve open and said exhaust valve closed, air through said restricted flow conduit will equalize the pressures on the two sides of said diaphragm, said air compressor will be unloaded and when the air pressure on the two sides of the diaphragm exerts less effective pressure over said exhaust valve than the 'bias of said spring on said diaphragm said diaphragm will snap to the open position of said exhaust valve and the closed position of said inlet valve and said air compressor will be eflect-ively activated.

References Cited in the file of this patent UNITED STATES PATENTS 122,544 Westinghouse Jan. 9, 1872 1,186,247 Ver Planck June 6, 1916 1,499,834 Lux July 1, 1924 1,806,925 Trapper May 26, 1931 2,023,418 Gustafson Dec. 10, 1935 2,216,855 Sanford et al. Oct. 8, 1940 2,252,418 Shelly Aug. 12, 1941 2,275,303 Mantle Mar. 3, 1942 2,283,311 Bevins May 19, 1942 2,731,975 Boals Jan. 24, 1956 FOREIGN PATENTS 207,592 Great Britain Nov. 26, 1923 

